Mechanical stoker



Feb. 9, 1932. A. M. HUNT 1,844,425

MECHANICAL STOKER Filed Feb. 19, 1929 2 sheets-sheet 1 m V m ATTORNEY Feb. 9, 1932. A. M. HUNT MECHANICAL sToKER d Feb. 19, 1929 2 Sheets-Sheet 2 INI INVENTOR M1/@Mal A TTORNE Y Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE .ANDREW M. HUNT, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO THE STANDARD STKER COMPANY, INCORPORATED, A CORPORATION OF DELAWARE MEGHANICAL STOKER Application filed February 19, 1929.

My invention relates to .mechanical stokers of the type comprising an oscillating fuel projecting and distributing member or socalled sweeper which acts directly to project the fuel into the iireboX and distribute it over the grate or llrebed; and the general object of the invention is to improve and simplify the controlling mechanism of said member or sweeper.

To the above and other ends which will hereinafter appear, the invention consists 1n the features of construction and combinations of devices and arrangements of parts hereinafter described and particularly pointed out in the appended claims.

The present form of the invention is more especially designed for use with a fuel sweeper adapted to oscillate within a conduit head or casing so as to gather up or collect the fuel as it is advanced through the conduit system and thereafter sweep or distribute it over the lirebed. TWith this type of oscillatory distrilnitor or sweeper it is practically essential, in order to obtain the best results, to vary its speed at different points or parts of its oscillatory movement. In the form shown the movement is in excess of a full circle, in the neighborhood of 4500 in extent; .During part of such movement, in the present case, the distributor is moving in opposition to the fuel advancing through the conduit system at which time the sweeper movement should be relatively slow; whereas another stage of the oscillatory movement should be :relatively fast, this movement stopping or ending quickly or abruptly, in order to effectively project and distribute the fuel over the lirebed.

Heretofore to provide for the variation in the speed of this general type of distributor, the train of devices for operating it has included complicated gearing and cam mechanism, or in this specific type of distributor shown in the drawings, the mechanism comprises an eccentrically mounted pinion or gearing and an intermeshing rack having a series of correspondingly varied teeth. These com-ltructions are subject to severe strains resulting in a rapidly wearing out or breaking of the parts.

Serial No. 341,212.

In carrying out my invention I have dispensed with speed varying devices of this sort in the operating train itself and have substituted therefor means imposing a variable resistance to the action of the operating train. While such means may involve different forms of construction, I have preferably employed, and have shown herein, resisting means comprising a plunger' or piston connected to the operating train and reciprocating in a chamber containing fluid, preferably oil, the chamber being so shaped as to impose varying resistances to the movements of the plunger, these resistances of course being co-ordinated with the sweeper so as to slow it down or speed it up at the desired points in its travel. In effect, it will be observed, there is provided a differential retarding mechanism for controlling the speed of an operative train of mechanism which would otherwise run uniformly assuming the source of power to be constant, but which as a result of being combined with the retarding mechanism is variably operated..

The invention will be described in detail in connection with the accompanying drawings which illustrate it in its preferred form and wherein Fig. l is a fragmentary vertical sectional view of part of a mechanical stoker embodying my invention, only so much of the stoker mechanism being disclosed as is necessary to a full understanding` of said invention;

Fig. 2 is a horizontal sectional view taken on a plane indicated by the section line 2, 2 in Fig. l looking downward, and with the cab licor removed;

Fig. 3 is a longitudinal sectional view on an enlarged scale showing part of the operating train of the sweeper and the differential retarder;

Fig. 4- is a vertical sectional view taken on a plane indicated by the section line 4, 4 in Fig. 3 and looking in the direction of the arrows at saidline; and

Fig. 5 is a vertical sectional view taken on the plane of the section line 5, 5 in Fig. 3 and looking in the direction of the arrows at said line.

The mechanical Stoker to which the invensupply.

As is well understood the stoker mechamsm comprises a conduit system and a feeding or conveying system, these systems beingv partly on the tender and partlyv on the locomotive and co-operating to advance the fuel from the source of supply to the fireboX. .The conduit system leading from the tender comprises a tubular section 16 in which is telescoped a second tubular section 17 connected by a universal joint 13 with a housing, riser or elbow member 19. :Said riser atits lower end has a curved elbow 2O and as it extends upward flares or expands outward as will be clearly apparent from Fig. 2.V At its upper end the riser is connected to a head or casing 21, which as herein disclosed, comprises side wall portions 22, a ioor or base portion 23 and sectional cover or top 24. As a whole the head or casing projects somewhat into the fire door opening 14 of the boiler, said opening above the hinged top 24 being normally "covered by a removable closure 25. The forward end of the conduit system may be suitably supported from the backwall 14, the supporting means comprising a bracket 26 connected to the riser 19 and anges 22a projecting laterally from the casing and suitably secured to the backwallll at the sides of the opening 14. The fuel feeding or conveyor system comprises flexibly connected screw conveyor sections, the forward section only being shown herein and designated by the numeral 27, this section terminating at or in the neighborhood of the elbow 20.

The screw conveyor system is rotated by a motor or engine not herein shown, as is well understood, the coal or fuel being thereby advanced through the conduit system and forced upward through the riser 19. The conduit and conveyor systems extend generally below the decks or floors of the locomotive cab and its tender, the conduit system rising above the cab deck just in rear of the boiler.

rlhe means for receiving and distributing the fuel fro-m the floor or table 23 of the conduit system comprises an oscillatory device or sweeping member, designated as a whole by the numeral 23, and in the form shown .com risino a hub ortion 29 a verticall i disposedarm 30 integral therewith and extending radially outward therefrom, and horizontally disposed top and bottom flanges 31 and 32 preferably integra-l with the arm, the

.whole constituting in effect a member I- shaped in cross section. it will be understood that other forms of distributors may be used equally as well with the novel operating mechanism of my invention.

T he sweeper is disposed so that as it rotates it will ust clear the floor plate 23 and to this end is secured to the upper portion of a vertically disposed shaft 33, the hub 29 being fitted over and suitably fixed to said shaft. The shaft is arranged just outside the boiler and is supported on radial and thrust bearings 34 which, together with the shaft, are enclosed and supported within a housing 35 at the under sidel of the base portion orfuel plate 23. Fixed to the shaft 33 between its VVbearings is a pinion 36 best shown in Fig. 3.

The pinion 36 is comprised in the train for operating the oscillatory member or sweeper 23, said train further comprising a rack bar 37 which constantly meshes with the pinion.

Securedto theleft-hand end portion of the rack bar is a piston rod 33 which passes leftward through a stuiiing box 39 and at its left hand end portion is secured to a piston 40 reciprocating in a chamber 41, these elements being comprised in a fluid pressure motor of suitable type for reciprocating the rack bar 37. The rack bar is disposed in an extension 35a of the housing 35. It will be seen that the operating train comprising the rack bar 37 and the -intermeshing pinion 36 which operatively connects the motor with the distributor sweeper are so constructed as to provide for uniform reciprocation or oscillation of the nsweeper without any variation in its speed so long as the operation of the actuating motor is uniform.

In order to obtain desired variations in the speed of the sweeper, there is provided novel means in the form of variable resisting or differential retarding `mechanism wherebyY the speed of the reciprocating rack bar 37 and of the sweeper which it actuates is controlled and varied. Said retarding means comprises a plunger or piston head 42 which is secured to the outer end of a. plunger rod 43,

the inner end of saidv rod being threaded or otherwise secured in the right-hand end` of the rack bar 37 in alignment with the piston rod 38. f

The plunger rod 43 passes through a stufiing box 44 secured toV a right-hand er:- tension 35b of the `housing 35 and which accommodates the rod 43. The plunger 42 reeiprocates in a chamber 45 which is secured to the extension 35b and is generally circular `in cross section but is provided at oneside with an extension 46 shaped to form a channel indicated at 47 which progressively varies in its transverse dimensions as clearly shown in Fig. 3, said channel being of greatest width at a point near each end portion of the chamber and abruptly diminishing in lll one dimension therefrom to each end of the chamber le to form in effect a cushioning or braking space 45 or 45h between thev piston head 4t2 and `the respective end wall of the chamber, and thence in the opposite direction the opening gradually decreases until it is at its narrowest at the middle portion of the chamber, if he chamber comprising the body portion or bore Ll5 and the extension l? may contain a fluid, as for example, oil. The construction is such that a variable resistance to the reciprocating or oscillating movements of the plunger' 42 is set up within the chamber, this resistance in turn effecting the speed at which the distributing or sweeping mechanism is operated. "he retardation of course varies with the resistance set up andthe speed varies inversely thereto.

lteferring to the operation of the mechanism it will be understood that the fuel is advanced through the conduit system by a motor operated screw conveyor independently of the motor of the sweeper mechanism, the fuel being deflected upward by the elbow 2O to the head or casing 2l and thence passing or dropping on to the fuel receiving plate or base 23 where it comes within the control of the sweeper or distributor 28.

In Fig. 2 the distributor is shown at one extreme or limit L of its oscillation and the parts are so proportioned and arranged thatI each oscillating movement is about i-500 in extent, carrying the member forward a little from each extreme and then backward to sweep up the fuel and `then forward again to project and distribute the fuel over the firebed, the movement from the L position stopping with the sweeper at the opposite extreme position L, from which it repeats its movement in reverse direction returning to the point Il. During such oscillating `inovements the fuel flows over on to the floor of the plate or base 23 and collects thereon in the path of the sweeper' and as the sweeper' approaches the fuel emerging from the conduit, on its return or backward movement in either direction, it is slowed down by the novel diiferential retarding mechanism con'iprising the plunger 42 and the ehan'iber flo with its variable extension 47, the minimum speed of the sweeper being reached at a point near the extreme rear of its path of movement. From this point on the movement of the distributor is in the direction of the fuel feed and accelerated, moving rapidly forward until its forward edge reaches the front of its firing door opening, when the projection of the fuel from it into the tirebox commences and continues throughout the greater part of the remainder of its movement. As the distributor approaches the terminal of its stroke its movement is abruptly checked and the fuel which then romains upon it or ahead of it is thrown toward a. corner of the iirebox, the distributor then completing its movement. The retarding mechanism is so proportioned and disposed as to effect this abrupt stopping of the distributor as it nears the end of its forward movement and to also effect the pro-` gressive retardation and acceleration of the distributor or sweeping mechanism at the desired points in its travel.

I claim:

l. In a mechanical Stoker, the combination with a iirebox having a tiring opening therein, of a fuel casing communicating with said firing opening, means for advancing fuel to the casing, means actuated independently of said fuel advancing means for projecting and distributing the fuel from the casing into the irebox, and means for variably retarding said independently actuated means throughout its cycle of operation.

2. In a mechanical Stoker, the combination with a freboX having a firing opening therein, of a fuel receiving casing communicating with said firing opening, means for advancing the fuel to the casing, a single continuously oscillating fuel distributing device for distributing the fuel from the casing into the firebox, a motor, a train of devices connecting' said motor with said distributing device, and variable retarding mechanism connected with said train of devices, said retarding mechanism comprising a reciprocatory plunger and a plunger chamber having an extension progressively varying throughout in dimensions transverse to the direction of movement of the plunger.

3. In a mechanical stoker, the combination with a ireboX, of a fuel receiving plate, means for advancing fuel to the plate, a single continuously oscillating fuel distributing device for distributing the fuel from the plate into the iireboX, a motor, a train of devices connecting said motor with said distributing device, and variable retarding' mechanism connected with said train of devices, said retarding mechanism comprising a reciprocating plunger and a hydraulic plunger chamber having an extension progressively varying throughout in dimensions transverse to the direction of movem'ent of the plunger.

l. In a mechanical stoker, the combination with a fireboX having a firing opening therein, of a fuel casing communicating with said opening', means for advancing fuel to the casing, a single continuously operating fuel distributor device for distributing the fuel from the casing into the firebox, a motor, a train of devices connecting said motor with said distributing device, and variable retarding mechanism connected with said train of devices arranged to vary the speed of said distributing device throughout its cycle of operation.

5. In a mechanical Stoker, the combination with a firebox having a firing opening therein, of a fuel casing communicating with said firing opening, means Afor advancing fuel to the casing, means actuated independently of said fuel advancing means for projecting and distributing the fuel from the casing into th'e firebox, and means arranged to offer a varying resistance -for variably retarding said independently` actuated means throughout its cycle of operation.

6. In a mechanical Stoker, the combination with a fireboX having a firing opening therein, of a fuel casing communicating With said `firing opening, means for advancing fuel to the casing, a single continuously oscillating fuel distributing device for distributing the fuel from the casingvinto theii'rebox, a Y

motor, a train of devices connecting said motor With said distributing device and means arranged to offer a varying resistance for variably retarding said train of devices throughout its cycle of operation.

7 In a mechanical Stoker, the combination wit-li a rebox, of a fuel receiving plate,

Vmeans for advancing the fuel to the plate, a single continuously oscillating fuel distributing device comprising a blade I-shapedV in cross section for distributing the fuel from the plate into the Firebox, a motor, a train of devices connecting said motor with said Vblade, Vand a resistor `connected With said train of devices, said resistor being arranged to oifer a. variable resistance for varying the speed of said distributing device throughout its cycle of operation.

' In testimonyvvhereof I ax my signature.

ANDREW M. HUNT. 

